1. Field of the Invention
The present invention relates to the field of holders for hand tools and specifically to those which use a collet to grasp the tool. Even more specifically it relates to such tools as re intended for use with threading taps.
2. Background Information
The conventional tap wrench, as used to tap threads by hand, is well known to machinists, mechanics and others who have need to perform this operation. The design of this wrench is almost constant across most if not all manufacturers. A cylindrical body is fitted with a sliding T-handle and one end and a set of tapered, somewhat flexible fingers at the other. The fingers are adapted to receive and grip the non-working end of a tap. A nut, fitted over the fingers threads on to the wrench and tightens against the fingers. A tapered inner surface on the nut forces the fingers together, gripping the tap.
This design suffers from several drawbacks. Most of these stem from the fact that significant rotational force is applied to the tap during the threading operation. This requires that the fingers both grip tightly and transmit this force to the tap without breaking. This combination requires that the fingers be relatively thick and broad and are typically hardened. This in turn limits their flexibility and thus the size range of taps which a particular wrench can grip. Because of this, it is common for a user to own two or more tap wrenches to accommodate a range of taps covering the common sizes from #0 through ½″.
Another side effect of the forces applied by the wrench is the required gripping force which must be applied to the tap. This typically requires that the nut be tightened by a wrench. This increases the setup time and requires the use of a tool in addition to the tap wrench in order to perform the operation.
A common characteristic of standard tap wrenches is that the T-handle must be removed for storage. If the handle is not removed, significantly greater space is required. If the handle is removed, it may become separated from the wrench and possibly lost.
There is a need for a tap wrench which can be quickly and securely fastened without the use of an external wrench. It should also accept a wider range of taps than is typical, preferably the entire range of #0 to ½″. Preferably, it will be approximately the same size and weight as a conventional wrench. Ideally, it would store in minimal space without removing the handle.